The present invention relates, in general, to a composition for dyeing material of synthetic aromatic polyamide fibers. More particularly, the present invention relates to such a dyeing composition comprising a cationic dye and a cyclohexenone, such as 2-cyclohexen-1-one,3,5,5-trimethyl.
Aromatic polyamides have become important synthetic fibers. More specifically, fabrics made of such fibers have long been recognized for their excellent fire retardancy characteristics in that the fabrics have very high melting points and do not ignite at temperatures above their char points. Accordingly, such fabrics are the primary material used by fire fighters, race car drivers, astronauts, and others who may be subjected to fire or to high temperatures.
The aromatic polyamides are the resultant, for example, of a condensation product of an aromatic diamine with an aromatic diacid halide. Examples of such condensation products are sold under the NOMEX trade name, such as NOMEX 430, NOMEX 450, and NOMEX 455, by E.I. du Pont de Nemours and Co.
However, satisfactory dyeing of such aromatic polyamide materials has been difficult. As a result, a dye assistant has been used in conjunction with a cationic dye. For quite some time, the primary commercial dyeing method employed acetophenone as the dye assistant.
The use of acetophenone as a phenyl alkyl ketone dye assistant, as well as the use of cyclohexanone as a cycloalkyl ketone dye assistant, in the dyeing of fabrics such as NOMEX with a cationic dye, is disclosed in U.S. Pat. No. 3,674,420 issued in 1972 to Sapers, assignor to Arkansas Company, Inc. Sapers also discloses that the dye assistant is admixed with a surfactant, such as a block copolymer of propylene oxide and ethylene oxide (sold as PLURONIC F-68).
Nevertheless, acetophenone, which has been commercialized, is objectionable as a dye assistant not only because of its health effects on personnel (acetophenone is classified as hypnotic), but also because of its strong odor that permeates the dye house and imparts a residual odor to the dyed fabric. Moreover, acetophenone corrodes equipment and pollutes water.
An improved dye assistant is disclosed in U.S. Pat. No. 4,780,105 issued in 1988 to White, Ensley, and Dalton, assignors to Stockhausen, Inc. More specifically, the ""105 patent describes a composition for dyeing material of synthetic aromatic polyamide fibers, where the composition includes (1) a cationic dye and (2) a dye assistant that is N-substituted phthalimide. The N-substituted phthalimide is admixed with an emulsifier, and preferably, the N-substituted phthalimide is a 2:1 mole ratio of N-butyl phthalimide and N-isopropyl phthalimide. Also preferably, the emulsifier is propylene oxide and ethylene oxide block polymer, and an anionic surfactant blend, and an anionic/cationic surfactant blend.
The disclosures of all of the mentioned patents are incorporated by reference.
Thus, a need still exists to find a dye assistant that is free from hypnotic effects (unlike acetophenone which is hypnotic), and yet is comparable to acetophenone.
Accordingly, the present invention provides a dyeing composition for dyeing material of synthetic aromatic polyamide materials, where the composition comprises (a) a cationic dye and (b) a cyclohexenone as a dye assistant. Preferably, the cyclohexenone dye assistant comprises a substituted cyclohexenone, more preferably, an alkyl-substituted cyclohexenone, even more preferably, a trialkyl-substituted cyclohexenone, and most preferably, 2-cyclohexen-1-one,3,5,5-trimethyl. The dye assistant may further comprise 3-cyclohexen-1-one,3,5,5-trimethyl.
While it is not intended to be bound to any theory, it is believed that the dye assistant operates via a mechanism that swells the synthetic aromatic polyamide materials.
Hence, it is an object of the present invention to provide a dyeing composition that employs a dye assistant that exhibits a satisfactory color yield and/or a color transfer.
Also, it is another object of the present invention to provide a dyeing composition that is free from hypnotic effects.
Some of the objects of the invention having been stated, other objects will become evident as the description proceeds, when taken in connection with the laboratory examples described below.
The dyeing composition of the present invention is useful for dyeing synthetic aromatic polyamide materials, such as those made from fibers such as those sold under the trade name NOMEX, for instance, NOMEX 430, NOMEX 450, and NOMEX 455. NOMEX is a manufactured fiber in which the fiber forming substance is a long chain synthetic polyaramide in which at least 85% of the amide linkages, namely xe2x80x94C(O)xe2x80x94NHxe2x80x94, are attached directly to 2 aromatic rings, for instance, phenyl rings.
Any cationic dye may be employed in the present invention.
Suitable cationic dyes are those mentioned in the above-noted patent to Sapers, such as Astrazon Olive Green BL and Astrazon Orange 3RL (also known, respectively, as Basic Green 6 and Basic Orange 27, and both formerly manufactured by Verona Dyestuffs) and those mentioned in the above-noted patent to White, Ensley, and Dalton, such as Basic Yellow 21, Basic Blue 41, and Basic Red 18 (further identified in the color index, third edition, published by the Society of Dyers and Colourists, Dean House, Piccadilly Bradford, Yorkshire, England). Also useful as cationic dyes are Red GL, Yellow 5GL, Blue X-3GL-300, and Red FB, sold under the trade name BASACRYL by BASF Corporation.
In order to improve the leveling of the dye upon the polyamide material, a dispersing agent selected from surfactants and/or emulsifiers may be employed, including those mentioned in the above-noted patent to Sapers and patent to White, Ensley, and Dalton.
For instance, the patent to Sapers mentions that the surfactant used can be either a cationic surfactant, a blend of a nonionic surfactant plus an anionic surfactant, or a blend of a nonionic surfactant plus a cationic surfactant. An example of a cationic surfactant that can be employed is a coconut trimethyl ammonium chloride. An example of an anionic surfactant that can be employed is a nonyl phenoxy ethanoxy ammonium sulfate. Examples of nonionic surfactants that can be employed are a nonyl phenol reacted with 30 mols of ethylene oxide and PLURONIC F-68 which is a block copolymer of polypropylene oxide and ethylene oxide.
Also, as mentioned in the patent to White, Ensley, and Dalton, the emulsifier may be a block polymer of propylene oxide and ethylene oxide. As also mentioned the surfactant may be an anionic surfactant, such as a blend of a diethyl sulfate quaternary of a fatty tertiary amine, ethoxylated nonyl phenol together with a dodecylbenzene sulfonic acid amine salt, and the surfactant may be an anionic/cationic blend of a dodecylbenzene sulfonic acid amine salt and a low cloud point ethoxylated nonyl phenol.
Furthermore, a very suitable emulsifier useful in the present invention is available under the trade name WITCOMUL 1305 from Witco Chemical. WITCOMUL 1305 is a modified ethoxylated fatty acid.
The dye assistant useful in the present invention comprises a cyclohexenone.
Preferably, the dye assistant comprises a substituted cyclohexenone, more preferably, an alkyl-substituted cyclohexenone, even more preferably, a trialkyl-substituted cyclohexenone, and most preferably, 2-cyclohexen-1-one,3,5,5-trimethyl. The last is available commercially from Creanova, Inc. as ISOPHORONE, which is a blend of two isomers, namely 98 weight % of 2-cyclohexen-1-one,3,5,5-trimethyl as the major isomer and 2 weight % of 3-cyclohexen-1-one,3,5,5-trimethyl as the minor isomer.
According to product information provided by Creanova, Inc., ISOPHORONE has the following properties in accordance with the Table below.
Suitably, the proportion of dye assistant to fabric ranges from about 2 to about 50 weight %. Additionally, a small amount, such as about 1 to about 2 weight %, of a salt, such as sodium nitrate or sodium chloride is recommended in the dye bath. Also, the pH of the dye bath is adjusted with acid to a range from about 2.5 to about 4.0, more preferably from about 2.6 to about 3.5, with a pH of about 3.0 being preferred. Suitable acids for the pH adjustment are formic acid, acetic acid, and citric acid.
The dye bath is heated, as is typical in the dyeing process, and the temperature may be in a range from about 270xc2x0 Fahrenheit (about 132xc2x0 Celsius) to about 250xc2x0 Fahrenheit (about 121xc2x0 Celsius). Also, as is typical during the dyeing process, after 1 or 2 hours at this high temperature, the temperature of the dye bath may be lowered to a temperature in a range from about 190xc2x0 Fahrenheit (about 88xc2x0 Celsius) to about 140xc2x0 Fahrenheit (about 60xc2x0 Celsius). As is well known, the dye bath may be pressurized, and the time and temperature varied, depending on the desired intensity of color.
The following examples are intended to illustrate further the invention, and the invention is not to be limited by these examples. Each % in the following examples is a weight %, as on the weight of the fabric (OWF).